A closed loop process controller

Abstract

The increasingly widespread use of programmable control systems in industry highlights the extent to which engineers are striving to integrate the traditional disciplines such as a mechanical-controlled plant with the latest computer technology. At one end of the scale, the logic requirements of small machine-tool applications are being met with a simple programmable logic controller. At the other end of the scale, there are now many large industrial plants, particularly in the iron and steel industry, where a computer-based control system has to cope with several thousand inputs and outputs, both analogue and digital, for alarm and control functions. As well as purely process control and monitoring functions, the system may also be required to produce management data. In between these two extremes are a great range of applications calling for varying levels of system capability. As the digital control field incorporates new technology, the development of new control tools is advancing at a rapid pace. The board-level microcomputer and the programmable controller are two types of controller spin-offs from today's technology. The board-level microcomputer is utilised in many areas normally associated with industrial control. These areas include special purpose product handling machines, instruments, material handling, computer front-ends, network interfacing, sequencing, interlocking, diagnostics, data collection, displays, etc. The popularity of the board-level microcomputer in industry is mainly due to the improved packaging concepts, a wide range of support chips, high level language support software, and improved software development systems. [...]